Cationic vesicles of a carnitine-derived single-tailed surfactant: physicochemical characterization and evaluation of in vitro gene transfection efficiency.

Spontaneous vesicle formation in water by single-chain surfactants is rare. Here we show that in aqueous solution, a single-chain cationic surfactant 3-(dodecylcarbamoyl-2-hydroxypropyl)-trimethylammonium chloride (C12-CAR) derived from D,L-carnitine spontaneously forms vesicles with hydrodynamic diameters in the range of 30-70 nm. A detailed self-assembly study of the C12-CAR surfactant was performed for the first time by use of a combination of techniques, including surface tension, conductivity, fluorescence probe, dynamic light scattering and transmission electron microscopy. The cationic surfactant was found to have a reasonably low critical aggregation concentration (3.4±0.2 mM) in water at 298 K. The vesicles were observed to be stable at the physiological temperature (310 K) over a long period of time. Although the vesicles formed were found to be unstable and exhibit vesicle-to-tubule transition in the presence of salt, in the presence of 10 mol% cholesterol the stability of vesicles is enhanced. When compared with lipofectamine-2000, the C12-CAR was found to act as an effective gene transfection agent in COS-1 cell line. The surfactant-DNA complex was also found to be nontoxic toward CHO cells.